Ulrich von Sax (born before 1204; died 23 September 1220) was Abbot of Saint Gall from 1204 until his death.
In 1208, a dispute arose with Werner von Staufen, the Bishop of Konstanz, concerning Castle Rheineck.
When Frederick II from the Hohenstaufen family moved to Germany in 1212, Ulrich met him and accompanied him to Basel.
Ulrich was in charge of Frederick's legation to Pope Innocent III who assigned him the right of wearing the mitre.
Together with his brother Heinrich, he built Clanx Castle and he also displayed extensive construction activity in Saint Gall by building a maternity home for poor women.